The human brain has an uncanny ability to focus on one voice in a sea of chatter, for example, at a party, but exactly how it does so is still up for debate.
"In the past, people have looked at the acoustic characteristics that enable the brain to do this," says Ingrid Johnsrude at Queen's University in Kingston, Ontario, Canada. "Things like differences in voice pitch or its timbre."
Johnsrude and her colleagues wondered if the familiarity of the voice also plays a role. Can people focus on one voice in a crowd more effectively if it belongs to a close relation? And is a familiar voice more easily ignored if we want to listen to someone else?
To find out, the team recruited 23 married couples. Each had been married and living together for at least 18 years.